The present application relates to a liquid crystal display module, and particularly to a liquid crystal display module having a main flexible printed wiring (FPC) board and an FPC board for a light source which boards are electrically connected to each other on the rear surface of the liquid crystal display module.
A liquid crystal display module has features of light weight, small thickness, and low power consumption as compared with a CRT (Cathode Ray Tube), and is thus used for display in many electronic devices. A liquid crystal display module displays an image by changing the orientation of liquid crystal molecules aligned in a predetermined direction by an alignment film resulting from a rubbing process by an electric field and thus changing an amount of light passing through a liquid crystal layer. A source of light made incident on the liquid crystal layer includes extraneous light in a reflective type liquid crystal display device and a backlight in a transmissive type liquid crystal display device. A reflective type liquid crystal display device has an excellent power-saving characteristic and has an advantage of high visibility under extraneous light. A transmissive type liquid crystal display device has an advantage of high visibility in a dark environment. A transflective liquid crystal display device combining characteristics of both a reflective type liquid crystal display device and a transmissive type liquid crystal display device is also known. A transmissive type or a transflective type liquid crystal display device is now often used as a liquid crystal display device because of the advantage of high visibility in a dark environment.
Such a transmissive type or a transflective type liquid crystal display device has a backlight unit on the rear surface of a liquid crystal display panel. A display module housing the liquid crystal display panel and the backlight unit in a casing is mass-produced in a module manufacturing plant, and the display module is incorporated into various electronic devices in an electronic device manufacturing plant. The liquid crystal display panel is electrically connected with a first FPC board for driving the liquid crystal display panel. The backlight unit is connected with a second FPC board for supplying power to a light source. Japanese Patent Laid-Open No. 2008-226965 (hereinafter referred to as Patent Document 1) discloses an application of a liquid crystal display module whose second FPC board for a light source is connected to a first FPC board for driving in order to reduce the number of connectors and the number of terminals connected to an external electronic device (see Patent Document 1 and FIG. 3).
A side of the liquid crystal display panel connected with the first FPC board has a driver IC and many pieces of wiring formed thereon, and thus has a wide non-display region. As shown in FIG. 3 of Patent Document 1 below, an LED as a backlight light source is disposed so as to be superposed on the wide non-display region as viewed in a plan in order to miniaturize the liquid crystal display module. Because the backlight unit is on the rear surface side of the liquid crystal display panel, the second FPC board for the light source is present on the rear surface side of the first FPC board for driving. Thus, generally, in the liquid crystal display module having the LED as backlight light source, the second FPC board is electrically connected to the rear surface side of the first FPC board.